Method and apparatus for fuel vaporising in catalytic fuel tank inerting

Abstract

A device for evaporating a liquid such as liquid fuel. The device comprises: a shell; means for supplying heat to the shell; a porous wick located in the shell so that there is a gap between an outer surface side of the porous wick and an inner surface of the shell; means for supplying liquid to the porous wick; and an outlet in the shell for vapour produced in the gap by the application of heat from the shell to the liquid in the wick.

The invention claimed is: 
     
       1. A fuel tank inerting system, comprising:
 a fuel tank; 
 a device for evaporating liquid fuel received from the fuel tank; 
 a catalytic device comprising a catalyst for combusting oxygen and fuel vapour and for supplying a product of the combusted fuel vapour to the fuel tank,
 wherein the device for evaporating liquid fuel comprises: 
 a shell; 
 a porous wick located in the shell so that there is a gap between an outer surface side of the porous wick and an inner surface of the shell; 
 means for supplying liquid fuel to the porous wick; and 
 an outlet in the shell for fuel vapour produced in the gap by application of heat from the shell to the liquid fuel in the wick, wherein the fuel vapor is directed from the outlet to a catalytic device, 
 wherein the wick includes a primary porous wick facing the inner surface of the shell, and a secondary porous wick located within the primary porous wick, the liquid fuel being supplied to the secondary porous wick, then from the secondary porous wick into the primary porous wick, so that the fuel vapour is produced in the gap between the porous wick and the shell by the application of heat from the shell to the liquid fuel in the primary porous wick, 
 the fuel tank inerting system comprising a means for supplying the heat to the shell of the device for evaporating liquid fuel, wherein the means for supplying the heat comprises a hot air supply obtained by cooling the catalyst of the catalytic device. 
 
 
     
     
       2. A fuel tank inerting system as claimed in  claim 1 , wherein the device for evaporating liquid fuel is attached to a reservoir for liquid fuel to be evaporated, the wick projecting into the reservoir so as to come into contact with the liquid fuel. 
     
     
       3. A fuel tank inerting system as claimed in  claim 2 , wherein the secondary porous wick projects into the reservoir and the primary porous wick does not project into the reservoir. 
     
     
       4. A fuel tank inerting system as claimed in  claim 1 , wherein means are provided to inject liquid fuel into the wick. 
     
     
       5. A fuel tank inerting system as claimed in  claim 1 , wherein grooves are formed on the outer surface of the wick for the transport of fuel vapour along the wick. 
     
     
       6. A method of fuel tank inerting, comprising:
 supplying liquid fuel from a fuel tank to a porous wick located within a shell so that there is a gap between an outer surface side of the porous wick and an inner surface of the shell; 
 supplying heat to the shell; 
 evaporating liquid fuel in the wick to produce fuel vapour in the gap by the application of heat from the shell to the liquid fuel in the wick; 
 collecting the fuel vapour produced in the gap and removing said vapour from the shell; 
 directing said vapour to a catalytic device comprising a catalyst for combusting the fuel vapor and oxygen; and 
 directing a product of the combusted fuel to the fuel tank, 
 wherein the wick includes a primary porous wick facing the inner surface of the shell, and a secondary porous wick located within the primary porous wick, the liquid fuel being supplied to the secondary porous wick, then from the secondary porous wick into the primary porous wick, so that the fuel vapour is produced in the gap between the porous wick and the shell by the application of heat from the shell to the liquid fuel in the primary porous wick, 
 wherein heat is supplied to the shell via a hot air supply obtained by cooling the catalyst. 
 
     
     
       7. A method as claimed in  claim 6 , wherein the heat is supplied to the shell by means of hot air circulating around the shell or within channels provided within the shell.